Arrangement for securing conductors of stator winding of dynamoelectric machine

ABSTRACT

An arrangement for securing the conductor bars of a distributed winding in place on the magnetic circuit of the stator element of a dynamoelectric machine is constituted by spaced-apart insulating pieces each including a heel portion engaged in a complementary configured recess in the stator iron and two tapered lateral projections which bear against the conductor bars only along tapered sides of the latter. The central surface portion of each conductor bar oriented towards the gap between the stator and rotor elements is left exposed. The advantage of the arrangement is that it enables the conductor bars to be brought closer to the rotor.

United States Patent [151 3,641,378 LeHenaff [451 Feb. 8, 1972 541ARRANGEMENT FOR SECURING [56] References Cited CONDUCTORS 0F STATORWINDING uNlT'Eb STATES PATENTS 0F DYNAMOELECTRIC MACHINE 3,235,7612/1966 Nohen ..310/192 X Inventor: Jacques Leflenaff, Paris, FranceAssignee: Compagnie Electro-Mecimique, Paris,

France Filed: May 22, 1970 Appl. No.: 39,760

Foreign Application Priority Data May 29, 1969 France 6917390 US. Cl...310/214, 310/196 Int. Cl. ..H02k 3/48 Field otSearch ..310/214, 192

Primary ExaminerD. X. Sliney Attorney-Pierce, Schefllcr & Parker [57]ABSTRACT An arrangementfor securing the conductor bars of a distributedwinding in place on the magnetic circuit of the stator element of adynamoelectric machine is constituted by spaced-apart insulating pieceseach including a heel portion engaged in a complementary configuredrecess in the stator iron and two tapered lateral projections which bearagainst the conductor bars only along tapered sides of the latter. Thecentral surface portion of each conductor bar oriented towards the gapbetween the stator and rotor elements is left exposed. The advantage ofthe arrangement is that it enables the conductor bars to be broughtcloser to the rotor.

6 Claims, 5 Drawing Figures ARRANGEMENT FOR SECURING CONDUCTORS OFSTATOR WINDING F DYNAMOELECTRIC MACHINE This invention relates to animproved mode for securing the active electrical conductors of a windingdistributed on the magnetic circuit of the stator element of adynamoelectric machine such as an electrical generator or motor.

It is known that the active conductors of such a distributed winding aregenerally lodged in slots extending generally parallel with the axis ofthe machine, and that the conductors are retained in their slots bymeans of chocks which are made from insulating material and sometimesfrom metal.

This known mode for securing the conductors in the stator slots does notpermit, by reason of the thickness of the chocks and the height of theattachment hooks of the chocks on the teeth of the magnetic circuit,bringing the conductors very close to the gap between the stator androtor. Consequently the conductors remain recessed in the slotsrelatively far away from the cylindrical inner surface of the stator.

It results that, when the conductors are traversed by currents a fairlylarge number of flux lines is enclosed directly around these conductorswithout traversing the gap and consequently without producing a fluxlinkage with the conductors of the revolving rotor. This fact results ina more or less high value of self-inductance of the leakage of each ofthe windings present with respect to one another.

This notion of self-inductance of the leakage take on a particularsignificance in the case of alternating current machines where onedesignates under the term leakage reactance, the product of theself-inductance by the pulsation of the currents. The leakage reactancewhich has an intrinsic magnitude related to the geometry of the slotscontributes to defining certain essential electrical characteristics ofthe machine such as internal voltage drop, dynamic stability and theshort circuit current. In certain cases, where particular operatingconditions are sought, such as small voltage drop, good stability, andhigh short circuit current, it can be useful to reduce the leakagereactance to a small value. For this it is necessary to bring theconductors in the stator as near as possible to the zone where theenergy exchanges occur, i.e., at the gap between rotor and stator.

The object of the present invention is to provide an improved mode forsecuring the conductors in the stator slots by means which arerelatively simple and which enable the con-- ductors to be located veryclose to the gap. To this end, each of the conductors, or conductorbundles is maintained in its slot in the stator only along the two edgesof its surface turned towards the gap, so as to leave exposed thecentral part of this surface.

Another object of the invention is to provide an improved mode forretaining conductors in the bottom of the stator slots by means oflateral insulating pieces fixed in the magnetic circuit of the statorbetween the various conductors and having, in their parts near the gap,lateral projections which press against the conductors only along theiredges, thus leaving the central parts of the conductor surfaces orientedtowards the gap.

The improved mode for securing the conductors in their slots offers theadvantage that the lateral insulating pieces used to secure theconductors in their slots do not involve addition of any furtherthickness to the interval included between the conductors and the gap.By this fact, the distance between conductors of the stator and those ofthe rotor is smaller than in the case of a dynamoelectric machine inwhich the conductors are fixed in their slots in a classical manner, andtherefore the leakage reactance is reduced.

The mode of fixing the conductors in their slots in accordance with theinvention also results in a certain reduction in the height of the teethestablished by adjacent slots, this reduction exerting a favorableinfluence on the reduction of the self-inductance of the leakage of theslot conductors.

Various embodiments of the invention will now be described in anonlimiting manner with reference to the accompanying drawings in whichthey are illustrated.

FIG. 1 is a view in developed transverse section of a part of the statorand rotor of a dynamoelectric machine in which the stator conductors arefixed in a classical, i.e., prior known manner.

FIGS. 2 to 5 are-views similar to FIG. 1 but illustrating various modesof slot conductor fixation in accordance with the invention.

With reference now to FIG. 1, there is depicted a part of the rotor land stator 2 of a dynamoelectric machine in which the rotor and statorconductors are lodged in their slots in a prior known manner. The rotorl is provided with slots 3 of a circular cross section extendinglongitudinally of the rotor axis opening in its cylindrical exteriorsurface 4. In the same manner, the stator 2 is provided withlongitudinally extending slots 5 having a rectangular cross sectionwhich open in the inner cylindrical surface 6 of the stator and whichdelimit between them the stator teeth 7 having a height h.

Rotor 1 is assumed to be of the type having a distributed winding andcomprises in each slot 3 an active conductor 8. In the same manner,stator 2 is provided with a stator winding composed of an activeconductor 9 (or a bundle of conductors) lodged in each longitudinallyextending slot 5. Each active conductor 9 is surrounded by insulation11.

The prior known mode of securing the stator conductors 9 in their slots5 includes chocks 12 of insulating material, the chocks having atrapezoidal cross section which engage longitudinal grooves 13 formed inthe extreme outer ends of the teeth 7 and delimiting, at the extremitiesof these teeth attachment hooks 14 for the chocks 12. In other words thechocks 12 are thus fixed in place at the sides of the teeth by dovetailassemblies. With this mode of securing the conductors 9, a relativelylarge distance a is established between the rotor conductors 8 and thestator conductors 9 which results in a substantial leakage reactance, aswas previously explained.

One embodiment of the improved mode for securing the conductors of thestator winding in their respective slots in accordance with theinvention is depicted in FIG. 2. In this figure, as well as in FIGS. 3to 5, corresponding components have been designated with the samereference numerals as those used in FIG. 1. In FIG. 2, the statorconductors 9 are secured within their respective slots 5 by lateralinsulating pieces 15 of generally prismatic configuration and atriangular cross section which extend longitudinally of the slots. Theseinsulating pieces 15 may be magnetic or nonmagnetic and each has aradial plane of symmetry xy. Each piece 15 is extending by a cylindricalheel 16 having a circular cross section whose axis is contained in theplane of symmetry xy. Also, each tooth 7 of stator 2 has a height hsmaller than the height h of the rectangular teeth 7 represented in FIG. 1. Each tooth 7 in FIG. 2 is formed with a V-shaped groove 17 in itsfrontal part, i.e., the part turned towards the gap between rotor andstator, in which is engaged a tapered part 15a of the lateral surface ofthe prismatic piece 15. The bottom of this V-shaped groove opens to acircular throat 18 sized to and which receives the heel 16 of piece 15.Also, the tapered part 15b of the lateral surface of the prismatic piece15 projecting outside the V-shaped groove 17 bears against the slightlytapered edge 9a of conductor 9 which projects radially inward beyond theopen end of the slot. In this manner, the prismatic piece 15 anchored inthe iron of stator 2 by its heel 16 lodged in throat l8 bears by itslateral tapered wall 15b on a tapered surface of conductor 9, thus tohold the conductor in slot 5.

By virtue of the fact that the pieces 15 are wedged in the teeth 7 ofthe stator 2, each pair of adjacent pieces 15 delimit, between theirfacing longitudinal edges, a space in which is lodged the frontal part11a of insulation 11 which is thus flush with the bases of the prismaticpieces 15. The result of this arrangement is that distance a, betweenconductors 8 and 9 of the rotor and stator respectively is smaller thanthe corresponding distance a (in FIG. 1) obtained with the prior knownmode of securing the stator conductors in their slots, this being due toelimination of the chocks 12. This reduction of the distance a involvescorrespondingly a reduction in leakage reactance. Also, the reduction inheight h of teeth 7 exerts a favorable influence on the reduction inself-inductance of the leakage of conductors 9.

The pieces 15 which ensuresecurity of the stator conductors 9 can have across section other than the triangular configuration depicted in-FIG.2. All that is necessary is that each piece be provided with a heel bywhich it can be wedged in the iron teeth on the stator and with lateralprojections which engage and hold each insulated conductor 9 in its slot5.

FIG. 3 illustrates an application of the principle depicted in FIG. 2 tohold, in the same slot 19, two juxtaposed insulated conductors 21 and22. In this case, each conductor 21, 22 has a single truncated edgewhich engages the external surface.

part 15b of the lateral wall of the adjacent prismatic piece 15.

FIG. 4 illustrates an application of the principle depicted in FIG. 2 tohold, in the same slot 25, two superposed conductors 24, 25. In thiscase, the innermost conductor 24 has a rectangular cross section and theoutermost conductor 25 has two truncated edges in contact with thesurface portions 15b of the lateral walls of two adjacent pieces 15.

FIG. illustrates an application of the principle depicted in FIG. 2which makes it possible to completely eliminate the iron teeth of thestator. In this case, each insulating piece 26 comprises a central part26a having a rectangular cross section, an outer part 26b having atrapezoidal cross section, and an inner part 26c of circular crosssection which is lodged within a throat 27 of the same size andconfiguration provided in the iron of the stator. Thus thecircumferentially spaced insulating pieces 26 project from the internal,nontoothed cylindrical surface of the stator and each trapezoidal part26b secures the corresponding sides of two adjacent conductors 9 as inthe case of the embodiment according to FIG. 2. The mode of securing thestator conductors in slots established between adjacent insulatingpieces 26 as depicted in FIG. 5 thus permits one to increase thedistance between the iron in the rotor and stator components of themachine.

The insulating pieces can be of a small axial length, or they can bequite long, according to manufacturing requirements. The insulatingproperty of the pieces 15 prevents them from becoming the seat ofcurrents induced in parallel in the slot conductors.

The lateral pieces can be made from other than insulating material; inthis case insulation in the longitudinal direction can be obtained bythe use of pieces of metallic foil, insulated on their faces and glued,the metal being magnetic or nonmagnetic.

In conclusion it is also evident that other forms of execution of theinvention can be developed from the principles disclosed in theapplication without imposing a limitation on the scope of the inventionas defined in the appended claims.

1. An arrangement for securing the conductors of a distributed windingin place within slots formed respectively between adjacent teethprovided on the stator element of a dynamoelectric machine and whichopen in the direction of l the rotor which comprises an insulating pieceindividual to each of said stator teeth, each said insulating pieceincluding a heel portion extending longitudinally of the correspondingstator tooth and which is secured within a complementary configuredrecess within the tooth and two tapered lateral projections alsoextending longitudinally of the stator tooth and engaged respectivelywith like tapered portions of the conductor winding extending radiallyinward beyond the open ends of adjacent slots.

said conductor winding in ad'acent slots. 3. An arrangement as de med inclaim 2 wherein the radially inner portions of said insulating piecesterminate flush with the radially inward ends of the conductor windingsin the slots.

4. Anarrangement for securing the conductors of a distributed winding inplace on an inner toothless surface provided on the stator element of adynamoelectric machine, said toothless surface extending substantially360 about the axis of the machine, which comprises a plurality ofcircumferentially spaced insulating pieces extending longitudinally ofthe stator, each of said insulating pieces including a longitudinallyextending heel portion secured within a complementary configured recessextending longitudinally within the body of the stator element such thatsaid insulating pieces project inwardly from said inner surface of thestator element to establish slotlike spaces receiving the windingconductors, the radially inner end portions of said insulating piecesbeing provided with tapered lateral projections engaged respectivelywith like tapered portions of the conductor winding located betweenadjacent insulating pieces.

5. An arrangement as defined in claim 4 for securing the conductors of adistributed winding in place on the stator element of a dynamoelectricmachine wherein each said insulating piece includes a middle portion ofrectangular cross section from one side of which said tapered lateralprojections ex tend and from the other side of which said heel portionprojects.

6. An arrangement as defined in claim 5 for securing the conductors of adistributed winding in place on the stator element of a dynamoelectricmachine wherein the said radially inner end portions of said insulatingpieces terminate flush with the radially inward ends of the conductorwinding portions located between the insulating pieces.

1. An arrangement for securing the conductors of a distributed windingin place within slots formed respectively between adjacent teethprovided on the stator element of a dynamoelectric machine and whichopen in the direction of the rotor which comprises an insulating pieceindividual to each of said stator teeth, each said insulating pieceincluding a heel portion extending longitudinally of the correspondingstator tooth and which is secured within a complementary configuredrecess within the tooth and two tapered lateral projections alsoextending longitudinally of the stator tooth and engaged respectivelywith like tapered portions of the conductor winding extending radiallyinward beyond the open ends of adjacent slots.
 2. An arrangement asdefined in claim 1 for securing stator conductors in place within thestator slots wherein each said insulating piece is constituted by aprism having a tapered cross section depending from the heel portionthereof and which forms said tapered lateral projections, a portion ofsaid tapered lateral projections being engaged with the sides of aV-shaped groove formed in the frontal face of each tooth, and anotherportion of said tapered lateral projection being engaged with saidradially inward extending tapered portions of said conductor winding inadjacent slots.
 3. An arrangement as defined in claim 2 wherein theradially inner portions of said insulating pieces terminate flush withthe radially inward ends of the conductor windings in the slots.
 4. Anarrangement for securing the conductors of a distributed winding inplace on an inner toothless surface provided on the stator element of adynamoelectric machine, said toothless surface extending substantially360* about the axis of the machine, which comprises a plurality ofcircumferentially spaced insulating pieces extending longitudinally ofthe stator, each of said insulating pieces including a longitudinallyextending heel portion secured within a complementary configured recessextending longitudinally within the body of the stator element such thatsaid insulating pieces project inwardly from said inner surface of thestator element to establish slotlike spaces receiving the windingconductors, the radially inner end portions of said insulating piecesbeing provided with tapered lateral projections engaged respectivelywith like tapered portions of the conductor winding located betweenadjacent insulating pieces.
 5. An arrangement as defined in claim 4 forsecuring the conductors of a distributed winding in place on the statorelement of a dynamoelectric machine wherein each said insulating pieceincludes a middle portion of rectangular cross section from one side ofwhich said tapered lateral projections extend and from the other side ofwhich said heel portion projects.
 6. An arrangement as defined in claim5 for securing the conductors of a distributed winding in place on thestator element of a dynamoelectric machine wherein the said radiallyinner end portions of said insulating pieces terminate flush with theradially inward ends of the conductor winding portions located betweenthe insulating pieces.